scholarly journals Improving of geometric precision in the manufacture of circular holes using technology WEDM

2019 ◽  
Vol 4 (1) ◽  
pp. 238-245
Author(s):  
Luboslav Straka ◽  
Gabriel Dittrich
Keyword(s):  
Process Parameters ◽  
Roughness Parameters ◽  
High Quality ◽  
Machined Surface ◽  
Geometrical Accuracy ◽  
Geometric Precision ◽  
Tool Setting ◽  
Circular Holes ◽  
Geometric Deviation

WEDM technology is among the final technology. It is characterized by the high quality of the machined surface. Therefore, a small geometric deviation from the desired shape, position, orientation or run out may have a significant impact on the functionality of the finished component. Its range is largely influenced by the accuracy of the applied electroerosion device, the precision of the workpiece and tool setting, the machining method, but also the combination of each other and the adjustment of all process parameters. They result in the final quality of the machined surface not only in terms of roughness parameters but also in terms of geometric precision of the machined surface. The aim of the paper was to describe the possibilities of improving the geometrical accuracy of WEDM with thin brass electrodes. At the same time, it contributes to an existing database of knowledge that defines the influence of selected aspects on the geometrical accuracy of the machined area in the production of circular openings.

scholarly journals Catalytic quality improvement of waste polyolefin originated fractions

2018 ◽  
Vol 5 (1) ◽  
pp. 12-18 ◽  
Author(s):  
O. Tóth ◽  
A. Holló ◽  
J. Hancsók
Keyword(s):  
Quality Improvement ◽  
Process Parameters ◽  
Diesel Fuel ◽  
Alternative Fuels ◽  
High Quality ◽  
Light Gas Oil ◽  
Fuel Blending ◽  
Quality Of Products ◽  
Middle Distillates

Abstract The demand for alternative fuels having low greenhouse gases emission is continuously growing worldwide. Therefore it is preferred to produce new, waste originated components. One option is the recycling of plastic waste with cracking. The produced hydrocarbon fraction is not suitable for fuels thus it is important to improve its quality. The aim of our experimental work was to study the quality improvement of this cracked fraction (PPCGO) and crude oil based middle distillates (different composition) with co-processing. Our goal was to produce high quality diesel fuel blending components. We studied the effect of process parameters on the quality of products. Ni (2.3%) Mo (11.0%) P (2.3%)/Al2O3 catalyst was used. During the experiments we studied the hydrogenation of olefins, saturation of aromatics and desulphurization. The hydrogenation of olefins was practically complete at 300°C. It took place at significantly higher speed than the desulphurization reactions. In case of light gas oil feedstock the products had significantly lower sulphur contents; below 10 mg/kg already at 340°C. We determined that the cracked fraction had beneficial effect on the performance properties of the products. In case of all feedstock combinations, we found process parameters which can be used to produce high-quality diesel fuel blending components on the tested catalyst.

Technology of Pulse Electrochemical Polishing of Stainless Steel

2010 ◽  
Vol 44-47 ◽  
pp. 3031-3035
Author(s):  
Zhi Yu Zhao ◽  
Guang Tao Zhou ◽  
Su Zhi Zhang ◽  
Bi Bo Xia
Keyword(s):  
Surface Roughness ◽  
Stainless Steel ◽  
Process Parameters ◽  
Pulse Frequency ◽  
Optimal Parameters ◽  
Electrochemical Polishing ◽  
High Quality ◽  
Important Method ◽  
Steel Sheets

Pulse electrochemical polishing is an important method to improve the surface quality of metal sheet. The reasonable control of process parameters is the key to obtain high-quality polishing. In this paper mechanism of pulse electrochemical polishing of stainless steel were studied using the stainless steel sheets of SUS201, SUS202, and SUS304. The influence of the current density, pulse frequency, duty cycle, and other factors on surface roughness were examined, and the optimal parameters was determined. The research results have directional meaning to the scale polishing of stainless steel-based in manufacturing enterprise.

Influence of Process Parameters on Geometric Precision of Machined Surface after WEDM

2017 ◽  
Vol 756 ◽  
pp. 107-118
Author(s):  
Ľuboslav Straka ◽  
Slavomíra Hašová
Keyword(s):  
Electrical Discharge ◽  
Electrical Discharge Machining ◽  
Negative Impact ◽  
Geometric Accuracy ◽  
Machined Surface ◽  
Influence Of Process Parameters ◽  
Geometric Precision ◽  
Geometric Size ◽  
Nominal Surface

Geometrical precision machined surface is generally understood as mainly precision shape, orientation, location and run-out. As a rule, it is measuring the appropriate deviations from the nominal surface. The geometric size of this deviation from the nominal surface can in practice affect the conventionally measured value for the dimension and the dimension whilst maintaining the required tolerance. Because the WEDM technology is among the most accurate technology, the small final geometric accuracy deviation has also a negative impact on the final quality of the machined surface. The paper aimed to describe errors geometrical precision of machined surface which occurs in wire electrical discharge machining (WEDM) and quantify their scope.

scholarly journals The influence of the constructive features of the plasmotron on the quality of the cut during air-plasma cutting of sheet metals

2020 ◽  
pp. 58-69
Author(s):  
S. V. Anakhov ◽  
◽  
B. N. Guzanov ◽  
N. B. Pugacheva ◽  
T. M. Bykova ◽  
...  
Keyword(s):  
Sheet Steel ◽  
Plasma Cutting ◽  
Sheet Metals ◽  
Air Plasma ◽  
Roughness Parameters ◽  
High Quality ◽  
Butt Welding ◽  
Steel Sheets ◽  
Thick Steel

The features of structure formation in the heat-affected zone, which are formed in the process of plasma cutting of 10 mm and 36 mm thick St3ps steel sheets, are presented. Cutting of thick steel is accompanied by high carburization, increasing hardness of the surface layer, and increasing surface roughness parameters. The research results allow us to conclude that the developed PMVR-9.1 plasmatron makes it possible to perform sufficiently high-quality cutting of sheet steel with a thickness of up to 40 mm and more. However, butt welding after plasma cutting without preliminary machining can be performed for a steel thickness of 10 mm.

Study of Si–Ge Interdiffusion in Laser Recrystallization of Ge Epitaxial Film on Si Substrate

2021 ◽  
Vol 13 (1) ◽  
pp. 1-9
Author(s):  
Chao Zhang ◽  
Jianjun Song ◽  
Jie Zhang
Keyword(s):  
Thermal Annealing ◽  
Process Parameters ◽  
Process Simulation ◽  
Epitaxial Film ◽  
Lattice Mismatch ◽  
Crystal Quality ◽  
Si Substrate ◽  
High Quality ◽  
Laser Recrystallization

Direct epitaxial growth of germanium (Ge) film on silicon (Si) substrate (GOSS) holds great potential in micro-electronics and optoelectronics. However, due to the 4.2% lattice mismatch between Si and Ge, it is difficult to directly obtain high quality Ge by epitaxy on Si substrate. Laser recrystallization technology provides a simple, efficient and low-cost way to improve the crystal quality of epitaxial Ge film grown on Si substrate. This technology is essentially a process of thermally induced phase transformation. By controlling the laser process parameters, epitaxial film of a certain thickness is melted, so that lattice rearrangement and recrystallization are achieved, and high-quality thin Ge/Si can be prepared. Laser recrystallization is a high temperature thermal process, and Si–Ge interdiffusion may detrimentally occur. In this paper, the mechanism of Si–Ge interdiffusion is discussed. Based on Fick's law of diffusion, a numerical model for Si–Ge interdiffusion of GOSS is established. On this basis, the process simulation of thermal annealing and laser recrystallization Si–Ge interdiffusion is carried out by Sentaurus Process simulation. The results show that compared with the traditional thermal annealing, the Si–Ge interdiffusion of Ge on Si almost does not occur in the process of laser recrystallization. By reasonably controlling the process parameters of laser recrystallization, the thin Ge film near the Si–Ge interface does not melt, which can not only improve the crystal quality of Ge epitaxial layer, but also effectively avoid the Si–Ge interdiffusion in the process of laser recrystallization. Through this research, we have aimed at predicting and control the Si–Ge interdiffusion, providing an important technical reference for the preparation of high quality GOSS by laser recrystallization technology.

scholarly journals ANALYSIS OF THE INFLUENCE OF TOOL ELECTRODE WEAR ON SURFACE QUALITY IN DIE-SINKING EDM TECHNOLOGY

2021 ◽  
Vol 2021 (2) ◽  
pp. 4388-4395
Author(s):  
LUBOSLAV STRAKA ◽  
◽  
PATRIK KUCHTA ◽  
Keyword(s):  
Indirect Method ◽  
Metal Particles ◽  
Tool Electrode ◽  
Electrode Wear ◽  
Roughness Parameters ◽  
Machined Surface ◽  
Significant Deterioration ◽  
Undesirable Consequence ◽  
The Given

During the electro-erosive process, metal particles are gradually removed not only from the machined material but also from the tool electrode. Here, the removal of material from the tool electrode is generally considered to be an undesirable consequence of the electro-erosive process. The extent of this wear can be relatively accurately quantified using several indicators. Of these, the percentage of loss of the working part of the tool electrode has the highest informative value. The resulting quality of the eroded area after die-sinking EDM also depends on the magnitude of the given parameter. Therefore, based on experimental measurements, the paper aimed to describe the performed analysis of the influence of the wear of the shaped tool electrode on the quality of the machined surface after die-sinking EDM in terms of surface roughness parameters. The wear of the shape tool electrode in terms of volume loss was measured by the indirect method through weight loss. Experimental results showed that when machining tool steel with a finishing operation, a much lower wear rate of the shape tool electrode was recorded compared to the roughing operation. At the same time, it was found that when the shape tool electrode wear exceeds the level of about 8%, there is a significant deterioration of all qualitative indicators of the machined surface.

Influence of technology parameters of free-cutting steel continuous casting on the billet internal structure

2020 ◽  
Vol 76 (2) ◽  
pp. 139-142
Author(s):  
A. T. Kunakbaeva ◽  
A. M. Stolyarov ◽  
M. V. Potapova
Keyword(s):  
Regression Analysis ◽  
Continuous Casting ◽  
Internal Structure ◽  
Sulfur Content ◽  
Manganese Content ◽  
High Quality ◽  
Correlation And Regression Analysis ◽  
Cutting Steel ◽  
Continuously Cast

Free-cutting steel gains specific working properties thanks to the high content of sulfur and phosphorus. These elements, especially sulfur, have a rather high tendency to segregation. Therefore, segregation defects in free-cutting steel continuously cast billets can be significantly developed. The aim of the work was to study the influence of the chemical composition of freecutting steel and casting technological parameters on the quality of the macrostructure of continuously cast billets. A metallographic assessment of the internal structure of cast metal made of free-cutting steel and data processing by application of correlation and regression analysis were the research methods. The array of production data of 43 heats of free-cutting steel of grade A12 was studied. Steel casting on a five-strand radial type continuous casting machine was carried out by various methods of metal pouring from tundish into the molds. Metal of 19 heats was poured with an open stream, and 24 heats – by a closed stream through submerged nozzles with a vertical hole. High-quality billets had a cross-sectional size of 150×150 mm. The macrostructure of high-quality square billets made of free-cutting steel of A12 grade is characterized by the presence of central porosity, axial segregation and peripheral point contamination, the degree of development of which was in the range from 1.5 to 2.0 points, segregation cracks and strips – about 1.0 points. In the course of casting with an open stream, almost all of these defects are more developed comparing with the casting by a closed stream. As a result of correlation and regression analysis, linear dependences of the development degree of segregation cracks and strips both axial and angular on the sulfur content in steel and on the ratio of manganese content to sulfur content were established. The degree of these defects development increases with growing of sulfur content in steel of A12 grade. These defects had especially strong development when sulfur content in steel was of more than 0.10%. To improve the quality of cast metal, it is necessary to have the ratio of the manganese content to the sulfur content in the metal more than eight.

Experience of clinical testing of personal telemedicine system ‘Obereg’ for remote monitoring of patients in intensive care units

2020 ◽  
pp. 52-58 ◽  
Author(s):  
A. A. Eryomenko ◽  
N. V. Rostunova ◽  
S. A. Budagyan ◽  
V. V. Stets
Keyword(s):  
Intensive Care ◽  
Intensive Care Units ◽  
Remote Monitoring ◽  
Clinical Testing ◽  
Transportation Of Patients ◽  
High Quality ◽  
Telemedicine System ◽  
Accuracy Of Measurements ◽  
Hospital Equipment

The experience of clinical testing of the personal telemedicine system ‘Obereg’ for remote monitoring of patients at the intensive care units of leading Russian clinics is described. The high quality of communication with the remote receiving devices of doctors, the accuracy of measurements, resistance to interference from various hospital equipment and the absence of its own impact on such equipment were confirmed. There are significant advantages compared to stationary patient monitors, in particular, for intra and out-of-hospital transportation of patients.

METHODOLOGICAL ASPECTS OF VISUALIZATION OF CORONARY ARTERIES WITH TRANSTHORACIC ECHOCARDIOGRAPHY

2018 ◽  
pp. 26-35
Author(s):  
Z. A. Agaeva ◽  
K. B. Baghdasaryan
Keyword(s):  
Blood Flow ◽  
Coronary Blood Flow ◽  
Coronary Arteries ◽  
Transthoracic Echocardiography ◽  
Second Harmonic ◽  
Anatomic Reconstruction ◽  
High Quality ◽  
Acoustic Window ◽  
Methodological Aspects

The transthoracic echocardiography made by multifrequency probes with support of the mode of the second harmonic imaging, is a competitive method for visualization of the main coronary arteries and allows to estimate coronary blood flow with high quality. Of course, the method has considerable restrictions, most important of which is the low spatial resolution of a method, due to small acoustic window. Because of this the transthoracic visualization of coronary arteries perhaps will not become the leading method of anatomic reconstruction of separately taken coronary artery and especially all coronary arteries system. However uniqueness and indisputable advantage of this method is an opportunity to noninvasively estimate a coronary blood flow both once, and in dynamics.

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